Drive-chain tension adjuster



June 24, 1930. Rjs. KELso DRIVE CHAIN TENSION ADJUSTEH Filed De, 3, 1925 A Patented June 24, 1930 RQCKFQRD, I LLINQIS, Asslelon up FREE SEWING MACHINE QRINEQHAIN :Camion-ADJUST@ s ,que forms thrs Support by suitable set screws 22 or other fastening means. It will be obvious that these collars prevent movement of the shaft 15 with respect to the bushing 20. The bushing is provided intermediate its ends with an integral ball portion 23 having a conical depression 24 in one side thereof. The ball portion 23 of the bushing ts snugly Within the 4opening 19, as shown. The bearing support 19 is provided at one side with a set screw 25 having a conical end 26 adapted to enter the depression 24. A lock nut 27 engages the face of the bearing support 18 to prevent movement of the set screw 25 as will be apparent. It will be apparent that the bushing 20 is adapted to shift its position, turning about the conical end of the set screw to assume a position truly coaxial with the shaft 15.

The bed plate is provided adjacent theV opposite end of the shaft 15 with an integral tubular member 28 arranged vertically and above the center of the shaft 15. A shank 29 lits snugly within the tubular member 28 and is adapted to be moved vertically therein. A suitablev set screw 30 is adapted to secure the shank 29 in any desired position. The shank 29 is provided at its lower end with a preferably integral bearing support 31 having an opening 32 therein arranged coaxial with the .shaft 15. The opening 32 is similar to the opening 19 of the bearing support 18 and is adapted to receive a similar bushing 33. The bushing 33 is also provided intermediate its ends with a ball portion 34 which iits snugly within the opening 32 and is adapted to be maintained in proper position by a set screw 35 `having a conical end 36 entering a f similarly shaped depression 37 formed in the bushing. A lock nut 38 is adapted to engage against the face of the bearing support 31, surrounding the screw 35 to prevent rotating movement of the latter. It will be obvious that theshaft 15 is mounted to revolve within the bushings 2O and 33. v

As clearly shown in Figure 2, the bushing 33 is provided with an axially extended portion 39 which projects a substantial distance beyond the bearing support at the side thereof opposite the sprocket 16. A substantially U-shaped yoke or stirrup 40 surrounds the extended portion 39 of the bushing, as shown in Figures 2 and 3. The upper ends of the stirrup are turned outwardly as at 41 and are adapted to be secured to the lower face of the bed plate by screws or the like 42. The base 43 of the stirrup is arranged a substantial distance beneath the extended portion of the bushing, as shown, and a screw 44 passes through the base 43. The upper end of the screw 44 is adapted to contactv with the extended portion of the bushing and is adapted to be fixed against rotation by a suitable lock nut 45.

The operation of the device is as follows:

The shaft 15 is adapted to be driven by the chain 17 passing about the sprocket 16, as will be understood. The chain 17 is driven from above by the rotating needle bar operating shaft which in turn may be driven by any suitable means such as an electric motor (not shown) The shaft 15 rotates in the bushings 20 and 33, each of the latter being adapt ed to pivot about its set screw to permit the bushings to be properly alined with the shaft. The chain 17 may be adjusted to the proper tension by loosening the set screw 30 and moving the support 31y downwardly until the proper tension is obtained, whereupon the set screw 30 may be tightened against the shank 29. It will be apparent that the tensioning of the chain tends to lift the outer end of the shaft-15 which in turn has a tendency to bow the shaft 15`downWardlybetween the bushings. The screw 44 then may be turned to elevate the projecting end 39 of the bushing 33 until the shaft assumes a straight position whereupon the lock nut 45 may be tightened.' If it is found that the tension placed upon the chain is too great,the set screw` 30 may be loosened and the shank 29 moved upwardly slightly. The screw 44 should be operated to properly line the shaft 15 when the chain 17 is at its proper tension, as will be apparent. Vertical movement of the shank 29 to vary the tension of the spring obviously will cause the bushings 2O and 33 to swing slightly about their pivots whereby the bushings at all times will aline with ythe shaft.l The ball portions of the bushings lit snugly within their openings to prevent play therein, but do not lfit suiiciently. tightly to prevent free pivoting movement Vof the bushing. f

It is to be' understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and-that various changes -in the shape,- size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of lthe subjoined claims.

I claim:

1. A device of the character describedcomprising a rotatable shaft, spaced bearing bushings surrounding said shaft, each of said bushings being provided with a substantially spherical v enlargement, supports for said bushings, said supports being providedwith cylindrical openings corresponding in diameter to said enlargements, a flexible driving element passing around said shaft adjacent 1 each of said'bearing supports, said enlargements being provided with depressions pivotally receiving the endsof said set screws.

2. A device of the character described cornprising a rotatable shaft, bearings for said shaft arranged near the ends thereof, said bearings being universally supported substantially centrally thereof, a flexible driving element passing about said shaft outwardly of and adjacent one of said bearings, means adjacent said last named bearing for adjusting it transversally to the axis of said shaft, means for correcting lateral flexing of said shaft between said bearings, comprising a lsubstantially U-shaped member having its base portion arranged adjacent said shaft andk provided with a threaded opening, and a set screw arranged in said opening, and adapted to contact with the inner end of the bearing adjacent said flexible element.

3. A device of the character described comprising a rotatable j shaft, spaced bearing bushings surrounding said shaft, one of said bushings having an inwardly directed extension, supports for said bushings, means for driving said shaft, and means contacting with said extension to exert a lateral force thereagainst to correct flexing of said shaft'.

4. A device of the character described comprising a rotatable shaft, spaced bearing bushings surrounding said shaft, supports for said bushings, one of said bushings having an inwardly directed extension, means arranged outwardly of sai-d last named bushing for driving said shaft, a substantiallyV U-shaped member having its base portion arranged adjacent said extension and provided with a threaded opening, and a set screw arranged in said opening and adapted to contact with said 0 extension to prevent flexing of said shaft.

In testimony whereof I aix my signature.

RALPH S. KELSO. 

